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Thanks so much both of you. That settles the argument. My friend who moved here same time as me and has just put her flat on the market was told by her estate agent she had to get a new one as they were only valid for 3 years. So she coughed up yesterday for a new one and won't believe me so I've just sent her Chris's link. The estate agent was either telling fibs or not au fait with the law, so a plonker whichever way you look at it. Thanks again boys:-)